Electric controlling apparatus



June 5, 1945. G. M. STAPLETON 2,377,726

ELECTRI C CONTROLLING APPARATUS Filed April 14, 1945 IN V EN TOR.

Jul 0 770/?AE y Patented June 5, 1945 ELECTRIC CONTROLLING APPARATUSGeorge M. Stapleton, Sea Cliff, N. Y., assignor to Ward Leonard ElectricCompany, a corporation of New York Application April 14, 1943, SerialNo. 482,979

6 Claims. (01. 172-289) This invention relates to apparatus for startinan electric motor by the sequential movement automatically of variousControlling parts, the control being dependent upon the change of thestarting current as the motor is brought up to speed.

The main object is to so interlock and interrelate the variouscontrolling parts as to insure their proper sequence of operation instarting the motor. Another object is to prevent at all times theimproper functioning of the apparatus even if it be attempted to actuatethe controllin parts improperly. Other objects and advantages of theinvention will be understood from the following description andaccompanying drawing which illustrates one embodiment of the inventionas v applied to the starting of a three-phase induction motor by firstconnecting its windings in star relationship and then in deltarelationship to the source.

The drawing is a diagram showing the various controlling parts andconnections and the mechanical and electrical interlockingrelationships.

The three-phase supply linesl, la and lb supply energy to thethree-phase motor windings 2, 2a and 2b. For this particular method ofstarting, the running contactor switch is composed of two setsoi threemovable bridging contacts, the upper set 3, 3a and 3b serving as lineswitch connections and the lower set 4, 4a and 4b serving to connect themotor windings in delta relationship. This contactor is moved to closedposition upon the energization of a relay winding 5 having an armature5a which actuates the bridging contacts to their closed or openpositions by connection to a cross bar 5b which in turn supports andinsulates the bridging movable contacts. When this switch is closed, thebridging contacts will engage fixed contacts which are connected to thesupply line and to the motor windings as shown.

The starting contactor is moved to closed posi-' tion upon theenergization of its relay winding 6 having a movable armature 6a whichin turn is connected to a cross member 6b. The bridging contacts of thestarting contactor are supported by and insulated from the cross member6b and are arranged in two sets of contacts, the upper set I, la and lbserving as line connectors and two of the lower set 8 and 8a serving toform the junction of the star connection. The righthand contact 81)serves to energize a controlling shunt relay and also the winding 6 ofthe starting contactor.

- The controlling shunt relay windin 9 is shown connected at oneterminal to the middle supply line la and a lead 9a from the otherterminal is connected to one of the fixed contacts engaged by thebridging contact 8b, the other fixed contact engaged thereby beingconnected through a starting button ill to an auxiliary fixed contact Ii of the running contactor. The fixed contact H is engaged by a movablecontact l2 when the runing contactor is open and in turn is connectedthrough a stop button l3 to the supply line i.

When the shunt relay 9 is energized and attracts its movable pivotedarmature 9b against the action of a restraining spring 90, a movablecontact 9d carried by the armature engages a fixed contact 9e. Thisfixed contact is connected to the fixed auxiliary contact ll of therunningcontactor; and the movable contact lid is connected to a terminalof the shunt winding 9.

The current or series relay comprises a winding I4 which is connected inseries with one of the motor windings when the starting contactor isclosed. When this series relay is energized it will attract a pivotedarmature l4a against the action of a restraining spring Nb and thencause its movable contact Me to engage a fixed contact Md. The movablecontact M0 is connected to one terminal of the winding 6 of the startingcontactor, the other terminal of the winding-6 being connected to thesupply line vIa. The fixed contact Md is connected to a terminal of thestarting button ill and to a fixed contact engaged by the bridgingcontact 8b of the starting contactor. When the series relay isdeenergized, it will cause a movable contact IE to engage a fixedcontact l5a. The fixed contact 15a is connected to the supply line Ithrough the stop button I3.

The movable contact i5 is connected to the movable auxiliary contact l6operated by the starting contactor; and when the latter is open, thecontact l6 engages a fixed contact lta which is connected to oneterminal of the winding 5 of the running contactor, the other terminalthereof being connected to the supply line, la. When the runningcontactor is moved to the closed position, it causes its movable contacti2 to engage a fixed contact I! which is connected to the movableauxiliary contact [6 of the starting contactor.

The armatures of the controlling shunt relay and of the series currentrelay are mechanically interlocked in any suitable manner so thatwhenever the shunt relay is deenergized, the armature of the seriesrelay is forced to its attracted position. In the drawing, forsimplicity of illustration, one end of the armature 9b is shownextending over one end of the armature Ha;

and, by reason of the force of the spring 90 overpowering the pull ofthe spring Mb, the armature 9b of the shunt relay forces the armature Haof the current relay to the position shown in the drawing whenever theshunt relay is deenergized. In this position the contact Ilc of thecurrent relay is in engagement with the fixed contact Md; and thecontact I5 of the relay is out of engagement with the fixed contact I50.

The drawing shows the parts in position for starting the motor. Thestarting is accomplished by merely closing the push button Imomentarily. This closes a circuit through the winding 6 of the startingcontactor by a circuit from the supply line I through the stop buttonI3, then through the movable contact I2 "of the running contactor to itsfixed contact I I and then through the lead I8 and the starting buttonIll through the contacts Md and I40 of the current relay through thewinding 6 of the starting'contactor and thence to the supply line Ia.This energization of the winding 6 results in closing the startingcontactor by moving its bridging contacts to engage their respectivefixed contacts. It also results in separating the auxiliary contact I6from the fixed contact I6a which introduces an additional break in thecircuit of the winding 5 of the running contactor. This electricalinterlock insures that the running contactor cannot be energized untilafter the starting contactor has moved to open circuit position.

The closing of the starting contactor closes the starting circuits ofthe motor and in this particular instance connects the motor windings 2,2a and 2b in star connection and causes the starting current of one ofthe motor windings to pass through the current winding I4 of the seriesrelay. These starting motor circuits may be traced as follows: from thesupply line I through the bridging contact lb, through the currentwinding I4 and through the motor winding 2 to a neutral connectionformed by the closing of the bridging contacts 8 and 8a; also from thesupply line Ia through the bridging contact Ia, through the motorwinding 2a to the neutral point; and also from the supply line lbthrough the bridging contact I and through the motor winding 22) to theneutral connection.

When the starting contactor closes, it also energizes the winding 9 ofthe shunt relay by a circuit from the supply line I through the stopbutton I3 and through the auxiliary contacts I2 and II of the runningcontactor, through the starting button I0, bridging contact 8b andthrough the lead wire I9 to the shunt winding 9 and thence to the supplyline Ia. This results in attracting the armature 9b of the shunt relaywhich moves the contact 90! into engagement with the fixed contact 9e.This maintains the shunt relay winding energized after the startingbutton I9 is opened, by a circuit from the supply line I through thestop button I3, contacts I2 and II, line I8 to the contacts 96 and 9dand thence through the relay winding 9 to the supply line la. Theenergization of the shunt relay also maintains closed the winding 6 ofthe starting contactor after the starting button ID is opened by acircuit from the supply line I, stop button l3, contacts I2 and IIthrough line I8 to the contacts 96 and 9d and thence through line I9 andbridging contact '8b through contacts Md and I40 and then through thestarting contactor winding 6 to the supply line la. The attraction ofthe armature 9b by the energization of the shuntrelay has no immediateeifect in mechanically releasing the armature of the current relaybecause the passage of the starting current through the current windingI4 serves to retain the armature Na in the position shown,

As the motor increases in speed the value of the starting currentgradually decreases to the dropout value of the current relay at whichtime the armature Ma is released. This separates the contact I40 fromthe contact I Id which opens the previously traced circuit of thewinding 6 of the starting contactor and permits this contactor to moveto the open position shown. This opens the motor starting circuits andalso causes the auxiliary movable contact IE to engage its fixed contactIlia. This results in closing the circuit through the winding 5 of therunning contactor by a circuit from the supply line Ia through thewinding 5, contacts IBa and I6 and through wire 20 to contacts I5 andI5a, which have been closed by the release of the armature of thecurrentrelay, and thence through the stop button I3 to the supply line I. Thisenergizetion of the winding 5 of the running contactor closes itsbridging contacts connecting the motor windings in delta, and therebybrings the motor to its normal running speed condition. These circuitsmay be traced as follows: from supply line I through bridging contactor3 to the motor winding 2a, thence through bridging contacts 4a and 3a tothe supply line Ia; also from the supply line Ia through the bridgingcontact 8a through the motor winding 21) and thence through the bridgingcontacts 41) and 3b to the supply line Ib; and also from the supply linelb through the bridging contact 312 through the motor winding 2 and tothe bridging contacts 4 and 3 to the supply line I.

The closing of the running contactor separates the auxiliary contact I2from the contact II which opens the maintaining circuit of the shuntrelay and thereby deenergizes this relay, permitting its armature 9b toforce the armature Ila to the position shown in the drawing by themechanical interlock of the armatures. This places the current relay inposition for enabling the starting of the motor again by the startingbutton after the running contactor is opened; and also introduces a,break in the circuit of the winding 5 so that the running contactorcannot be closed during the starting operation until the startingcurrent has been reduced to the proper value. The separation of theauxiliarycontact I2 from its contact II also introduces a break in thecircuit to the starting button In so'that even if this button be closedit cannot have any efiect upon the starting contactor and therebyprevents the closure of the starting contactor whenever the runningcontactor is closed. The closure of the running contactor also moves theauxiliary contact I2 to engage the fixed contact I1 and this maintainsclosed the circuit of the winding 5 of the running contactor by acircuit from the supply line la through the winding 5, auxiliarycontacts Ilia and I6 of the starting contactor, thence through contactsI1 and I2 and through the stop button I3 to the supply line I.

The motor is stopped by momentarily opening the push button I3 whichopens the maintaining circuit of the winding 5 of the running contactorand causes the parts to assume the position shown in the drawing.

It is apparent from the foregoing that the starting contactor cannot beclosed unless the running contactor is open and therunning contactorcannot be closed until the starting contac the current relay after thecurrent has been reduced to the proper drop-out value. Furthermore byreason of the mechanical interlock of the controlling relays, the shuntrelay when deenergized, places the armature of the current relay inposition to permit the energization of the closing winding of thestarting contactor by the starting button provided the running contactoris open; and after the shunt relay is energized it permits the currentrelay to release its armature at the proper value of starting current tothereby deenergize the Winding of the starting contactor and energizethe winding of the running contactor. The control provides low voltageprotection at all times during the starting and running periods.

Although this improvement is disclosed as applying tothe starting of aninduction motor by changing its windings from star to delta connection,it may readily be applied to other starting methods such as to theremoval of starting resistances from the motor circuit, the changing oftransformer connections and various other methods of control. Alsovarious modifications of this disclosure may be made for adaptation toparticular requirements without departing from the scope of theinvention.

I claim:

1. Motor starting apparatus comprising an electromagnetic startingcontactor, a current relay subjected to the starting current of themotor, said relay in the attracted position of its armature having apair of engaged contacts in the exciting circuit of the magnet of thestarting contactor, and a controlling relay having its armaturemechanically interlocked with the armature of said current relay forforcing the armature of the current relay to its attracted position whenthe controlling relay armature is in its unattracted position, saidcontrolling relay having its energizing circuit dependent upon theclosing of said starting contactor for thereby attracting its armaturefor mechanically releasing the armature of the current relay forenabling the armature of the current relay to be moved to itsunattracted position upon the starting cur-- rent of the motordecreasing to the drop-out value of the current relay and therebyseparating said engaged contacts for deenergizing said startingcontactor.

2. Motor starting apparatus comprising an electromagnetic startingcontactor, an electromagnetic running contactor, a current relaysubjected to the starting current of the motor, said relay in theattracted position of its armature having a pair of separated contactsin the exciting circuit of the magnet of the running contactor, and acontrolling relay having its armature mechanically interlocked with thearmatureof said current relay for forcing the armature of the currentrelay to its attracted position when the controlling relay armature isin its unattracted position, said controlling relay having itsenergizing circuit dependent upon the closing of said starting contactorfor thereby attracting its armature for mechanically releasing thearmature of the current relay for enabling the armature of the currentrelay to be moved to its unattracted positionupon the starting currentof the motor decreasing to the drop-out value of the current relay andthereby closing said separated contacts for energizing said runningcontactor.

3. Motor starting apparatus comprising an electromagnetic startingcontactor, an electromagnetic running contactor, a current relaysubjected to the starting current of the motor, said relay in theattracted position of its armature having-a pair of engaged contacts inthe exciting circuit of the magnet of the starting contactor and havinga pair of separated contacts in the exciting circuit of the magnet ofthe running contactor, and a controlling relay having its armaturemechanically interlocked with the armature of said cturentrelay forforcing the armature of the current relay to'its attracted position whenthe controlling relay armature is in its unattracted position, saidcontrolling relay having its energizing circuit dependent upon theclosing of said starting contactor for thereby attracting its armaturefor mechanically releasing the armature of the: current relay forenabling the armature of the current relay to be moved to itsunattracted position upon the starting current of the motor decreasingto the drop-out value of the current relay and thereby separating saidengaged con tacts fcrdeenergizing said starting contactor and closingsaid separated contacts for energizing said running contactor.

4. A motor starting apparatus comprising an electromagnetic startingcontactor, a current relay subjected to the starting current of themotor, said relay in the attracted position of its armature having apair of engaged contacts in the exciting circuit of the magnet of thestarting contactor, a controlling relay having its armature mechanicallyinterlocked with the armature of said current relay for forcing thearmature of the current relay to its attracted position when thecontrolling relay armature is in its unattracted position, a startingswitch, said controlling relay having its initial energizing circuitdependent upon the closing of said starting switch and of said startingcontactor for thereby attracting its armature for mechanically releasingthe armature of the current relay for enabling the armature of thecurrent relay to be moved to its unattracted position upon the startingcurrent of the m0- tor decreasing to the drop-out value of the currentrelay and thereby separating said engaged contacts for deenergizing saidstarting contactor, said controlling relay having contacts closed uponits energization for maintaining closed its own energizing circuit andthe energizing circuit of the starting contactor after the opening ofsaid starting switch, and the deenergization of said controlling relaybeing dependent upon the separation of said engaged contacts and theopening of the starting contactor.

5. Motor starting apparatus comprising an electromagnetic startingcontactor, an electromagnetic running contactor, a current relaysubjected to the starting current of the motor, said relay in theattracted position of its armature having a pair of engaged contacts inthe exciting circuit of the magnet of the starting contactor and havinga pair of separated contacts in the exciting circuit of the magnet ofthe running contactor, a starting switch, and a controlling relay havingits armature mechanically interlocked with the armature of said currentrelay for forcing the armature of the current relay to its attractedposition when the controlling relay armature is in its unattractedposition, said controlling relay having its initial energizing circuitdependent ii'pon the "closing 'or said switch and of said startingeontaetor for thereby attracting its armature fo'r'r'n'echanicallyrele'asing the armature or the tux-rent relay forenabling the armature or the-current relay to be moved to it'sunattr'acted position u' 'on the starting current of the motord'erea'sihg to the drop-out 'value of the current 'relay and therebyseparating said engaged contacts for "decnergizing said startingcontactor "and closing said separated contacts for energizing saidrunning contactor, said controlling relay having contacts closed uponits energiz'atio'n for m'aintaining closed its own energizing oirciiitand the energizing circuit of the starting -"contractor after theopeningof said starting switch, and the deenergization of saidcontrolling relay beihg'dependent upon the separation of said engagedcontacts and the opening of the starting c'o'nt'a'ct'or and the'ciosirig of the running cbntactor.

6. Motor starting apparatus cbmiifisihg an electromagnetic startingcon-tactor, an "electromagnetic running conta'ct'or, "a, current relaysubjected to the starting current of the motor, said relay in theattracted po'siti'onoi "its armature having a "pair of engaged contactsin the exciting circuit of the magnet of the starting contactor andhaving a pair of separated contacts in the exciting circuit of themagent of the running contactor, a starting switch, and a controllingrelay 'h'a'ving its armature mechanidaily interlocked with the armatureof said current relay for forcing, the armature or the current relay toits attracted position when the controllmg relay armature 1's in itsunattracted position, said controlling relay having its initialenergizing circuit dependent upon the closing of said switch and of saidstarting contactor for thereby attracting its armature formechanicallyreleas'ihg the armature of the current relay for enablingthe at-mature of the current relay to be moved to its unattra'ctedosition upon the starting current of the motordecreasing to the"separated contacts for energizing said running conthctor, saidcontrolling relay having contacts closed upon its energization formaintaining closed its own energizing circuit and the energizing circuitof the "starting contactor after the opening of said starting switch,the ener- -gization of said controlling rela'y being dependent upon theseparation of said engaged contacts and the openin of the startingcontaotor,

and auxiliary contacts separated upon the cloaing of the runningcontactor for introducing a break in the circuit of said starting switchand in the maintaining circuit or said controlling relay.

GEORGE M. STAPLETON.

